Progressing cavity pumps and motors have been used for decades in pumping and hydraulic motor applications. The typical assembly consists of a rigid rotor which resembles a screw having multiple leads. The rotor mates with a stator which has one additional lead cut on the interior of the stator. The differences in the leads form cavities between the rotor and the stator. These cavities continually progress from one end of the stator to the other when the rotor is turned. Operation of the pump is achieved by mechanically turning the rotor, while operation as a motor is achieved by forcing fluid into the end cavity to turn the rotor.
A stator is conventionally an elastomeric or plastic material which is formed by injection molding into the outer sleeve-shaped tube or housing. The elastomeric or plastic material is conventionally bonded with the tube, typically with an adhesive for a polymeric stator, and by welding for a metal stator insert. The bond provides a fluid seal between the stator material and the outer tube or housing.
The use of metal stator inserts is substantially limited in progressing cavity pumps and motors. The use of an adhesive for bonding the plastic or elastomeric material of a stator to the outer housing limits the use of the stator to an operational temperature and chemical environment required by the adhesive. Accordingly, the use of progressing cavity pumps and motors with a plastic or elastomeric stator has heretofore been limited.
The disadvantages of prior art are overcome by the present invention, and an improved progressing cavity pump or motor is hereinafter disclosed.